Circuit changer



Oct. 6, 1925.

' 5. 5. STOLP CIRCUIT CHANGER Filed Aug. 18, 1921 fgi.

Patented Oct. 6, 1925.

UNITED stares 1,556,176 PATENT OFFICE;

SAMUEL s. sToLr, OF CHICAGO,- ILLINOIS, ASSIGNOR TO CHEATHAM ELECTRIC SWITCH- ING DEVICE so, 01: LOUISVILLE, KENTUCKY.

CIRCUIT CHANGER.

Application filed August 18, 1921. Serial No. 493,258.

3 To all whom it may conce n:

Be it known that I, SAM'UEL S. Sronr, a citizen of the United States, and resident of Chicago, county of Cook, and State ot Illinois, have invented certain new and useful Improvements in Circuit Changers, of which the following is a specification, and which are illustrated in the accompanying drawings, vforming a part thereof.

The invention relates to circuit changers, meaningithereby apparatus "for selective operation of an electrical device in one of a plurality of different ways, in accordance with predetermined conditions, as, for example, the automatic electro-magnetic setting of the switch points of electric railway tracks in different positions in accordance.

with the approach of the car under power and without power, respectively.

The object of the invention is to provide an improved circuit changer which comprises an assembly of simple pieces oi apparatus but which shall be certain oi operation in the desired manner under all circumstances, and free from objectionable arcing at the contacts or overheating in the coils.

In the accompanying drawings Fig. 1 is a diagram illustrating-the improved circuit changer as applied to an automatic switching device for D. 6. electric railroads,some ot the mechanical parts of the apparatus being conventionally represented;

Fig. 2 is side elevation of a form of trolley contactor which may be used with the apparatus illustrated in Fig. 1, a plarality of different positions of a trolley wheel in passing the contactor being indicated by dotted lines; and

Fig. 3 is a transverse sectional view of the trolley contactor taken on the line 33 of Fig. 2, one position of the trolley wheel being shown in full lines.

The overhead trolley wire of a D. C. electric railroad is shown in the digram (Fig. 1) at 10. The trolley pole of a car is conventionally represented at 11, and the heater, lighting and motive power circuits of the car are indicated in diagram at 12, 13 and 14,. respectively. A movable switch point of the track designed to direct the car for continued travel on the main line 15, or to take the siding 16, is conventionally rep resented at 17. As is customary in automatic switching devices, the movable switch point 17 is moved between its two posit1onsby the in and out-travel of the core 18 of a'double wound solenoid 19. For this purpose the solenoid core is operatively connected to the said movable switch point through the links 20 and 21, and an intermediate swinging knuckle 22. I

In accordance with the usual practice in theoperation Of D. C. automatic switching ..ClGVlOS, the setting of the movable switch point 17 in its two positions is determined by the, approach of the car with power oil and power on, respectively. A trolley contactor or so-called pan, generally designated 23, 1s mounted, as usual, on the trolley wire 10 in position'to beengaged by the trollev wheel, as 24:, of the car in advance of the eligagement of the wheels of the car with the switch.

' Should it be desired to prevent a dilterent' setting of the switch point 17 by a following car until the first car has traveled a givendistance beyond the switch, a second trolley pan 25 may be provided. In this connection it will, of course, be understood that the trolley 10 branches at the switch. and that in case the second trolley pan 25 is employed one of these pans will be mounted upon each branch of the trolley beyond the switch. For simplicity of illustration, however, the branching of the trolley is omitted on the drawing and but one pan 25' is shown. In event use of the second trolley pan 23 is not desired, the movable arm 26 of a double throw switch, shown in the drawing as connecting the left-hand contact'27 of the switch with the center Contact 28, will be set to the opposite position in which it connects the center Contact 28 with the right-hand contact 29, or the said double throw switch will be omitted entirely and the wire leading to contact 29 will be connected as shown for the wire leading from center contact 28.

In accordance with the usual practice one of theside bars, as 30, ot the trolley pan 23 is connected to the trolley wire 10 through the coil of the main selector relay, as 35. For this purpose wires 36 and 37 lead from trolley wire 10 to relay 35, and wire 38 leads from relay 35 to the side bar of the trolley pan 23. As usual the winding of relay comprises only a few turns of coarse wire, and the lifting of the armature 3 1 of this relay is accomplished only in event current is drawn from the side bar 30 of the trolley nan by the power circuit, as 14. of the car,the current used in the heater and light circuits 12 and 13 of the car not being sufficient to lift the armature 3,,

In carrying out the present invention the other side bar, as 31, of the trolley pan 23 is connected by wire 39 to a high resistance relay 40, preferably constructed for delayed release of its armature, as 41, by having a copper sleeve 42 mounted on its core. a The other side of the slow acting relay 40 is grounded, as through wire 43 and resistance coil 44.

hen the twoside bars 30 and 31 of the trolley pan 23 are both engaged by the trolley wheel, as 24, of the car, current is furnished to one or the other of the two windings 32, 33, of the double wound sole noid 19 directly from the trolley wire 10, in accordance with the setting of armature 34 of relay :5. For this purpose Wire 36 is extended through 3 and fuse 46 to the armature 41 of relay 40, and front contact 4'? of relay 40 is connected by wire 43 to a nature 34 of relay 35. The front and back contacts 49 and of relay 35 are connected to the two windings 32 and 33 of solenoid 19, as usual, except that to insure the holding of armature 34 after it has been lifted the connection of front contact 49 with w'iding is through a second front contact, as 52, for relay 40, and the connection of this contact with wire 39, as

wire It follows that as soon as the armature of relay 40 is lifted trolley current is being supplied to both of the side bai 30, 31, of the pan and relay 35 is shunted out. An inadvertent or emergency chan e of operation from power on to or vice versa, while current is beed to one or the other of the two k of the double wound solenoid 19, will accordingly have no effect in changing the position of armature 34 of relay 35.

Should the car come to rest with the trolley wheel 24 engaged with the pan 23, a change of operation, as from power off to power'on when starting the car, will cause movement of the armature 34 of relay 35 in case it occurs after armature 41 of relay 4O H has fallen, but it will then have no effect in ehangl the position of switch point 17, or do damage on account of arcing at the corresponding contact 49 or 50, for no current is then being furnished to either winding of solenoid 19. On the other hand, should the movement of the trolley wheel 24 across the pan 23 be very rapid, the disengagement of the trolley Wheel from the pan cannot cause premature release of armature 41 of relay 40 for the reason that when front contact 52 of relay 40 is closed current is being supplied to relay 40 directly from the trolley wire, as through wires 36 and 45, fuse 46, armature 41, front c t 52 and wire 53.

of the armature 41 of relay 4O ient length of time to insure comsaturation of the selected Winding of d is allthat is required in any ule it will be understood that this readily accomplished by equipped with a dash pot in a well known he arrangement illustrated is prefei d because it also serves to prevent an in'iproper second ,n'iovement of the switch point 1"? under any circumstances.

shown, one of the windings, as 54, of a double wound relay is connected by wire to front contact 47 of relay 40. The other side of winding 54 of relay 55 is grounded through wire 57 and resistance coil l i hen front contact 47 of relay 40 is closed current is accordingly supplied to winding 54 of relay 55, the current path being from trolley wire 10 through wires 36 and fuse 46, armature 41, front contract 47, wire 56, and through wire 57 and resistance coil 58 to ground. Armature 59 of relay is thereby lifted, closing front contact- 60 and shunting out relay 40. For this purpose armature 59 is connected either to wire 36 or to wire 39, in accordance With the setting of the double throw switch arm 26 or the omission of the said switch, as already explained, and front contact 60 of relay is connected by wire 61 to wire 43 through a second winding 62 on relay 55. lt l1; been found in practice that the resistance of windin 62 on relay 55 may be about live per cent of the resistance of re lay to insure shunting out of the relay 40 -1611 front contact 60 of relay is closed.

The arrangement ust described provides three time factors tending to delay the release of relay 46 as follows; 1 "-t 2; t e tn e interval required for lifting the t 1" o after ocular" l i found in practice to (lose the circuit at front contact 47 of relay 40 for a suflic t gi'h of time to insure co nlete sa iration of the noid 19.

is the current will be broken at an selected winding of solefurnished to solenoid 19 front contact 47 of relay when armature 41 is released, it will be understood that contact 4'? should be equipped with a magnetic blow out devi in a well known manner. On the other hand, as neither of the contacts 49, 50, of relay 35 will ever be opened under any circumstances when front contact 47 of relay 40 is closed, due'to the shunting out of relay 35 by the closing of front contact 52 of relay 40, there will never be any arcing at contacts 49 and 50, notwithstanding any inadvertent or emergency change of operation of the power circuit 14 of the car, or from any cause.

Since relay 40 is shunted out when front contact 60 of relay 55 is closed, there can be no further operation of the switch point 17 until the armature 59 of relay 55 has been released. In the arrangement shown this does not occur until the. trolley wheel 24 comes incontact with pan 25. For this pur pose one of the side bars 63 of pan is directly connected to the trolley wire 10, as at 64. The other sidebar 65 of pan 25 is connected by wire 66 to wire 61. It follows that when the two side bars 63, 65, of pan 25 are connected by the engagement of the trole ley wheel 24 with both bars, trolley current is supplied to winding 62 of relay 55 from both sides of the same, and since the circuit through the winding 54 of relay 55 was opened at front contact 47 of relay 40 when armature 41 was released, the armature 59 of relay 55 will now be released and the parts are all restored to normal for a new operationof-the switch point 17 when another car approaches. s

As the protection afforded by the use of the pan 25 will not often be required, this pan will usually be omitted and the double throw switch arm will be set to engage termina-l 29 or wire 39 will be directly connected to armature 59 of relay 55. In that case the circuit through winding 62 ofrelay 55 will be'opened by the electrical separa tion of the side bars 30, 31, of pan 23. The armature 59 of relay 55 will accordingly be released when the trolley wheel 24 leaves the pan 23, or, in the event of such a rapid move ment of the trolley wheel 24 over the pan that delayed release of armature 41 has not yet occurred, as soon thereafter as the circuit through .winding 54 of relay 55 is opened at front contact 47 of relay 40.

Since current required for the o eration of solenoid 19 is not drawn from t e pan 23, no arcing occurs upon the electrical separation of the two side bars and31 of the pan. Arcing at the pan can accordingly be entirely avoided even when current for the power circuit 14 of the car is being drawn from the side bar 30 of the pan, if the construction of the pan is such that the trolley wheel 24 is engagedwith the side bar 30 before leaving the trolley wire 10 and is then reengaged with the trolley wire 10 before leaving the side bar 30. A pan of this construction isillustrated in detail inFigs. 2 and 3. As there shown the two side bars 30 and 31 of the pan take the form of-angle irons applied tothe adjacent faces of a wooden support 67. This support is grooved along its under side, as at 68 (Fig. 3), to receive thetrolley wire 10 upon which it is firmly held in any convenient manner, as by clamping bolts 69.

If now the two side bars 30 and 31 of the pan are bent upwardly at their opposite ends, as at 70 and 71 (Fig. 2) the trolley wheel 24 will be depressed for disengagement with the trolley wire 10 only upon becoming engaged with the curved end portions 70 of the side bars 30 and 31. Similarly the trolley wheel 24 will become reengaged with the trolley wire 10 before it becomes disengaged from the curved end portions 71 of the side bars 30 and 31. Since operation of relay 40 in advance of the operation of relay isto be avoided, sidebar 31 of the pan 23 is preferably formed with an insulated section 72 at its forward end. Pan 25, when used, may be of the same construction as pan 23, but the formation of either of the side bars 63 and 65 with an insulated section is not required.

The statements heretofore made concerning the effect upon the apparatus resulting from bringing the car to .rest when the trolley ,wheel 24 is in engagement with the pan 23, refers more particularly to engagement of the trolley wheel with that part of the pan which is located beyond the insulated section'72 of side bar 31. Should the car come to rest with the trolley wheel 24 engaged with the insulated section 72 of side bar 31, the switch point 17 of the switch will not yet have been set and, on starting the car, automatic operation of the switch for main line will be impossible. However, for this operation of the switch movement of the car under suflicient headway to carry the trolley wheel entirely across the pan is contemplated in any case. On the other hand, continued application of the trolley wheel 24 to the pan, in line with the insulated section 72 of side bar 31, will do no harm, for the power circuit 14 of the car will not be closed when the car is at rest,

- and only the amount of current required by the heater and light circuits 12, 13, of the car will be drawn through relay 35.

Fuse46'is providedto avoid breaking an unduly heavy fiow of current at contact 47 of relay 40, in case of a short circuit in one of the windings of solenoid 19. Likewise the resistance coils 44 and 58 serve to protect relays and from overheating, it being quite possible to employ suflicient' resistance in eath of these coils to cause relays 40, and 55 to remain substantially cold even under continued application of current thereto. As a further precaution tov insure the operation of. relay 35, when required, in advance of the operation of relay 40, the

front and baclt contacts 49 and 50 of relay are preferably adjusted to provide only a short air between the armature and core of the re .ty and a correspondingly short range of movement of the armature between the contacts 49 and 50, whereas the arn'iature of relay 40 will be adjusted for a substantially greater amount of movement.

tlwiiig to the fact that the circuit through. the appropriate coil or 33 of solenoid 19 is opened as soon as the delayed release of armature 41. of slow acting relay 40 occurs, no limiting resistance is required to protect these coils. Except in the case of coil 35, which is in circuit with coil 51, these coils may be placed directly across the line and their full power at the voltage employed is available for moving the part to be shifted, as the switch point. 17. Furthermore, the res ance of coil 51 may be so low as to be almost negligible in limiting the amount of current supplied to toil it has been determined by experiment that the delayed release of armature 41 gives sufficient time for full saturation of the particular coil or of solenoid 19 which is in circuit with. it, and that further application of current to these coils does not serve any useful purpose.

Relay 40 is shunted out when armature 59 of relay 55 is lifted, if the resistance of coil 62 of relay 55 is about five per cent of that of relay 40. For this purpose relay 40 may be made of 500 ohms resistance, and coils 54 and 62 of relay 55 may each be made of 25 ohms resistance for either a 250 or 690 volt circuit. Limiting resistances 44 and 58 may each be of 500 ohms resistance for a 250 volt circuit, and 1500 ohms for a 600 volt; circuit.

The operation of the improved circuit changer is as follows :--Assu1ning switch blade 26 to be. in the position shown and there is no car between the pans 23 and 25, the engagement of trolley wheel 24 of an approaching car with pan 23 has as its first effect to draw current through relay 35. This is accomplished by contact of the trol ley wheel 24 with side bar 30 of the pan. The circuit is then from trolley wire 10, through wi es 36 and 37 to relay 35, and from relay 35 through wire 38, side bar 30, trolley wheel 24 and trolley pole 11 to ground. In event the car is coasting the amount of current thus drawn through relay35 will not be sufficient to lift armature 34 and. this armature will remain in its lowered position. 011 the other hand, in event the car is approaching the switch with power on, the amount of current drawn. through relay 35, when trolley wheel 24 engages side bar 30 of the pan, will be sufiicient to energize relay 35 and armature 34 will be lifted.

When the trolley wheel 24 has moved into the pan a. sufficient distance to also engage side bar of the pan, an additional path.

limiting resistance 44 to ground. Relay 40 is ac: ordingly energized and its armature 41 lifted to close contacts 52 and 47. This occurs regardless of the condition of the car to power on or power off. When armature is lifted there is a direct path for current from the trolley wire 10 through wire 36, fuse 46, armature 41, contact 47, 48, and armature to one or the other the windings 32, of solenoid 19, de-

ding upon the position of armature 34.

application of power to solenoid 19 continues for so long armature 41 remains in its litted position. In order that the application of power to solenoid 19 shall not be of too short duration on account of a rapid movement of trolley wheel 24 through the pan, current is supplied to relay 40 di rectly from, the trolley wire-10, when armature 41 is lifted. Such a direct path for current is provided through contact 52 and wire However, when armature 41 has been lifted relay 40 is immediately shunted out by the energiaation of relay 55 and the lifting of its armature 59.

The path for current through relay 55, when armature 41 is lifted, is through contact 4. wire 56, winding 54 of relay 55, wire 5?, and limiting resistance 58, to ground. The shunting out of relay 40 by the lifting of armature 59 of relay 55 arises from the fact that current is now supplied, directly from the trolley wire 10, to both sides of relay 40. The path for current to relay 40, through. armature 59 of relay 55, is from switch pole 27, through switch blade 26, to s witch pole 2S and thence to armature 59, from contact 60, through winding 62 of relay 55, and wires 61 and 43 to relay 40. The duration of the application of power to solenoid 19 is accordingly determined by the time interval required for the lifting of armature 59 of relay 55, after armature 41 of relay 40 has been lifted, and by the retarded release of armature 41 after relay 40 has been shunted out.

ll hen relay 40 has been shunted out by th lifting of armature 59 of relay 55, there can be no further application of power to either winding of solenoid 19 until armature 59 is again released. With the switch blade 26 in the position shown, this does not'occur until the trolley wheel 24 comes in contact with the corresponding pan 25. The path for current is then from trolley wire 10 through side bar 63 of pan 25, across the trolley wheel 24 to side bar 65, and thence through wires 66 and 61 to winding 62 of relay 55.' As both sides of winding 62 of relay 55 are thusdirectlyconnected to the trolley wire 10, and winding 54 of relay 55 .is open, this relay is shunted out and armature 59 is released. I

In case the apparatus is used with switch blade 26 engaged with switch pole 29, arma: ture 59 of relay 55 is released when the trolley wheel 24 leaves the pan 23, or as soon thereafter as winding of relay 55 is opened at contact 47 of armature all. In other words, when switch blade 26 is in the position shown, winding 62- of relay 55 is supplied with current directly from the trolley wire 10 and armature 59 is held until winding 62 is shunted out by the engagement of the trolley wheel 24 withthe pan 25. Ch the other hand, when switch blade 26 is engaged with switch pole 29, winding. 62 of armature 55 is supplied with current from the pan 23, and this current supply continues only while the trolley wheel 24; is engaged with pan 23.

I claim as; my invention:

1. [in electric switch-operating device comprising, in combination, an electric circuit including the track solenoid and a switch controlling the circuit, a circuit changer operable upon the said circuit to direct current into different parts of the track solenoid, and means for closing the said switch controlling the circuit operable also to shunt out the circuit changer.

2. In an electrical switch-operating device, in combination, a' switch operating circuit, a circuit changer therefor not included in the circuit, and means for shunting out the circuit changer when the switch operating circuit is closed.

3. In an. electrical switching device, in combination, a divided switch-operating circuit, a circuit changer therefor having an operating coil and a holding coil, the holding coil of the circuit changer being included in the corresponding branch of the said switch-operating circuit, and means; shuntingv out theoperating coil ofthe circuit changer when either branch of the said switch-operating circuit is closed.

15 d In an electrical switch-operating device, the combination with the track solenoid, trolley wire and trolley contactor, of a divided circuit extending directly from thetrolleywire'to the two parts of the track solenoid, a, circuit changer controlling the two branches of the said divided-circuit having an operating coil and a holding coil, the holding coil-ofthe circuit changer being included in the corresponding branch of the said divided circuit, and a circuit extending. from the trolley wire to the trolley contactor including the operating coil of the circuit changer.

5. "In an electrical switch-operating device, in combination, a source of power, a trolley contactor comprising two elements adapted to be electrically connected by the engagement therewith of the trolley wheel of a car, a divided switch-operating circuit extending from the source of power, a

circuit changer operable between the two circuit.

6. In an electrically controlled switchoperating mechanism, in combination, a trolley wire, parallel contact strips adjacent thereto, a trolley wheel adapted to pass from said trolley wire to said contact strips, a circuit changer circuit closed by contact of the trolley wheel with the said contact strips, a grounded circuit including one of said contact strips and the winding of an electromagnet, a track solenoid circuit connected with the trolley wire and including the armature of the electromagnet, and a shunt from said solenoid circuit to one of said contact strips, whereby the circuit changer is rendered temporarily inoperative when the track solenoid is closed.

7. In an electric switch operating device, the combination with the trolley wire, track solenoid and trolley contactor, of a normally open circuit not including thetrolley contactor connecting the trolley wire and track solenoid, a retarded release relay in circuit with the trolley contactor for closing the said normally open circuit and means automatically operable afterpick up of the retarded release relay for shunting out said re ay. 1

8. In an electric switch operating device, the combination with the trolley wire, track solenoid and trolley contactor, of a normally open circuitnot including the trolleycontactor connecting the trolley wire and track solenoid, a relay in circuit with the trolley contactor for closing the said normally 0 en circuit and means automatically opera 1e after pick up of the relay for shunting out said relay.

9. In an electrical switch operating device, in combination, a source of power, a contactor for-engagement by the traveling contact element of a car, a circuit changing relay having front and back contacts and an operating and a holding coil, a circuit extending from the source of 'power to'the ontactor,. through the operating coilof the circuit changing relay and a divided switch operating circuit having the front contact and the holding coil of the circuit changing relay in one of its branches and having the back contact of the circuit changing relay in another branch thereof.

10. in an electrical switch operating device, in combination, a source of power, a contactor comprising a pair of parallel conductors adapted to be electrically connected by the engagement therewith of the traveling contact element of a car, a circuit chang ing relay having front and back contacts and an operating and a holding coil, a circuit extending from the source of power to one of the conductors of the contactor through the operating coil of the circuit changing relay, a divided switch operating circuit having the front contact and the holding coil of the circuit changing relay in one of its branches and having the back contact of the circuit changing relay in another branch thereof, and another relay connected to the other conductor of the contactor for controlling the switch operating circuit.

11. In an electrical switch operating device, in combination, a source of power, a contactor comprising a pair of parallel conductors adapted to be electrically connected by the engagen'ient therewith of the traveling contact element of a car, a circuit changing relay having front and back contacts and an operati and a holding coil, a cir cuit eiztending "rom the source of power to one of the conductors of the contact-or 'i the operating coil of the circuit cha 0 1g relay, a divided switch operating circuit having the front contact and the holding coil of the circuit changing relay in one of its branches and having the back contact of the circuit changing relay in another branch thereof, and a retarded release relay connected to the other conductor of the contactor for controlling the switch operating circuit.

12. The combination with a contactor and the traveling contact element of a car cooperating therewith, of switch operating means operable upon engagement of the said traveling contact element with the contactor, Jeans preventing a second operation of the switch operating means, two restoring means controlling the said preventing means, one thereof being operable upon separation of the said traveling contact elenr it and cont-actor and a double throw switch controlling the said two restoring means.

13. The combination with a contactor and the traveling contact element of a car cooperating therewith, of a switch operating circuit closed by the engagement of the said traveling contact element with the contactor, means for opening the switch op erating circuit after a predetermined interval, and means preventing a second closing of the switch operating circuit while the traveling contact element is engaged with the contactor.

la. The combination with a contactor and 1c traveling contact element of a car cooperating therewith, of a switch operating circuit closed by engagement of the said traveling contact element with the contactor, means for opening the switch operatin ciruiit alter a prede ermined interval, and two selecti ely operable means preventing a second closing of the switch operating circuit, one thereof acting only while the said trai' 'eling contact element is engaged with the c ntactor.

The combination with a contactor and the trav li g contact element of a coop herewith, of a switch operating circuit closed by the engagement the said traveling contact elen'ient with the contactor, means for opening the switch operating circuit after a predetermined interval, two selectively operable means preventing a second closing of the switch operating circuit, one thereof acting only while the said traveling contact element is engaged with the contactor, and a double throw switch controlling the selection of the said two preventing means.

16-. The combination with a pair of contactors and the traveling contact element of a car cooperating with the two contactors in succession, of a switch operating circuit closed by the engagement of the traveling contact element with the first contactor, means for opening the switch operating circuit after a predetermined interval, and two selectively operable means preventing a second closing of the switch operating circuit, one thereof acting only while the said travel ing contact element is engaged with the first contactor and the other acting upon engagement of the said traveling contact element with the second contactor.

17. The combination with a pair of contactors and the traveling contact element of a car cooperating with the two contactors in succession, of a switch operating circuit closed-by the engagement of the traveling Contact element with the first contactor, means for opening the switch operating circuit after a predetermined interval, two selectively operable means preventing a second closing of the switch operating circuit, one thereof acting only while the said traveling contact element is engaged with the first contactor and the other acting upon engagement of the said traveling contact element with the second contactor, and a double throw switch controlling the selection of the said two preventing means.

18. An electric switch operating device comprising, in combination, an electric circuit including the track solenoid and a switch controlling the circuit, a circuit changer operable upon the said circuit to direct current in different parts of the track solenoid, a relay for closing said switch, and an auxiliary circuit closed by said switch for locking the relay in and shunting the circuit changer out.

19; An. electric switch operating device comprising, in combination, an electric circuit including the track solenoid. and a switch controlling the circuit, a. circuit changer operable upon the said circuit to direct current in different parts of the track solenoid, a relay for closing said switch, an auxiliary circuit closed by said switch for locking the relay in and shunting the circuit changer out, and a second relay operated upon the closing of said switch to shunt out the first relay. I

20. In an electric switching device, the combination of a source of power, a track solenoid, a normally open divided circuit including the source of power and-the track solenoid, a switch for closing said circuit, a

" circuit changer for directing current into different branches of said divided circuits and including a coil, means for closing said switch including a coil, an auxiliary circuit including said coils and a contactor having two elements adapted to be electrically connected by a trolley wheel, and means operated by the closing of the switch for locking in the second coil and shunting out the first coil.

21. In an electric switching device, the combination of a source of power, a track solenoid, a normally open divided circuit including the source of power and the track solenoid, a switch for closing said circuit, a circuit changer for directing current into different branches of said divided circuits and including a coil, means for closing said switch including a coil, an auxiliary circuit including said coils and a contactor having two elements adapted to be electrically connected by a trolley wheel, means operated by the closing of the switch for locking in the second coil and shunting out the first coil, and additional means operated by the switch for shunting out the second coil.

22. In an electric switch operating device, the combination with the track solenoid, trolley conductor and trolley contactor, of a normally open circuit connecting the trolley conductor and track solenoid,a relay normally in circuit with the trolley contactor and having two front contacts, one

controlling the said normally open circuit and the other connecting the relay with the trolley conductor'independent of the trolley contactor and means for shunting out the relay.

23. In an electric switch operating device, the combination with the track solenoid, trolley conductor and trolley contactor, of a normally open circuit connecting the trolley conductor and track solenoid inde pendent of the trolley contactor, a relay normally in circuit with the trolley contactor and having two front contacts, one controlling the said normally open circuit and the other connecting the relay with the trolley conductor independent of the trolley contactor, and means for shunting out the relay.

SAMUEL S. STOLP. 

